Dissertation

Summary

The « Plaine Mothaise », plays an important role for controlling water flow and quality of the Sèvre Niortaise River and constitutes a reservoir of biodiversity. Evolutions in agricultural practices induce replacement of more than 25 % of grassland by crops and poplars these last ten years. This affects habitats, resources and finally the biodiversity services. the aim of this project is to estimate the impact of changes by studying two soil macrofauna taxa, the terrestrial isopods and the carabids contributing to ecosystems functioning: isopods as decomposers, recycling organic matter, and carabids as polyphagous predators. These bio indicators allow a diagnosis concerning the quality of the ecosystem and its functioning. A plot and landscape scale survey is carried out in order to evaluate these impacts on individuals, populations and communities. At the plot scale we consider available housing environments and the effects of the agricultural practices. The neighbouring landscape elements such as non-crop area and crop mosaic dynamic will be taken into account.